(Click on Image for Slide Show of Process)
The idea came from an article in a gardening magazine. I was already changing the way I gardened in the back yard, adding raised beds and converting lawn sprinkler heads into drip irrigation distributors. Why not give a corner over to a small straw bale garden and see what I might grow there? My approach to gardening has always been about trying something new and learning from my experiments. The uncertainties of gardening make it fun for me. Introducing new elements only heightens the challenge.
The author of the magazine article had some specific reasons for creating her straw bale garden – aside from the vegetables she expected to harvest. She utilized a spot in her yard where the soil was so poor she had never grown anything but weeds in it. By the following year it was covered in a thick layer of rich compost "replete with fat and happy worms." She figured she could revitalize another plot with a straw bale garden each year, progressively improving her whole yard.
Then I was instructed to sprinkle a granular organic fertilizer on the top surface of the bales, followed by a 2-3 inch layer of compost. The hole in the center was filled with a mixture of compost and top soil (which I had brought in for the new raised beds nearby). The straw bales were to be watered every day for 10 days with a liquid organic fertilizer. I used liquid kelp. This was to "cook" the straw, causing it to start to break down to better accommodate plant roots.
After 10 days the bales were planted. I put in three tomato plants, two indeterminate varieties on the rear corners of the square, and an early season determinate on one front corner. On the other front corner, I planted an artichoke I had picked up on impulse at the garden center. (One year I experimented with artichokes in a conventional garden; I found they needed a longer growing season than I had allowed for.) The magazine article writer had grown a huge summer squash bush. I decided to seed a couple of winter squash varieties that would produce vines to trail down from the straw bales into the yard. A couple of eggplants I had grown from seed completed the "garden."
The center cavity seemed to invite root vegetables to grow in its deep, rich, loose filling. I opted for parsnips, which have no chance of penetrating the heavy clay of my conventional garden. Because parsnips are slow to germinate, the seed packet always recommends mixing in some radish seeds with them to mark the rows. The radishes germinate quickly and can be harvested by the time the parsnips are getting started. I mixed in seeds of several varieties. I also had on hand some seed for daikon, the long white radish loved and grown in Asia. I figured I had the perfect spot for them and seeded a couple rows.
Then I laid a length of soaker hose over the straw bales, looped it a couple times across the center, and began a schedule of almost daily watering. I continued applications of the liquid kelp several times through the summer.
The results: I harvested fruit from all of the plants except the artichoke, which grew only a few leaves. The tomato plants were not as large as the same varieties growing in the ground, nor did they produce as much fruit. The same was true of the eggplants and squash. I ate the small radishes in my salads, but the parsnips weren't planted early enough to grow beyond the size of a small carrot. The daikons flourished. They grew to the full depth of that center cavity, and when they reached the rabbit wire on the bottom, they began growing upwards, protruding from the surface of the soil.
Some findings:
- In 10 days of fertilizer treatments the straw didn't break down much. The "composting" process probably works better where the climate is not so dry as ours. (The magazine article writer lived in the coastal area of northern California.) When I planted, the holes I made in the straw didn't seem all that inviting for plant roots. There was moisture from the irrigation, of course, and I worked some of the compost from the surface into the straw. Next time I might add some soil, as well.
- For the same reason, even a year later, the straw is not composted. The bales have "melted" a little, but still retain their shape. I expect to replant them again this year. (Because the weather has been so cool, most of this year's planting is still on hold.)
- Typical weeds were not a problem. Those that came with the compost were easily pulled. But the straw produced its own weeds. This was wheat straw and it contained enough wheat seed to keep me pulling wheat grass most of the season.
Straw bale gardening is not a new idea. Seeing mine, an elderly neighbor told me he had tried it once – without success; I didn't question him on his process. On the Internet I found numerous references, some describing variations from the process I followed. Most of the reasons for straw bale gardening are similar to those of my magazine article writer, but there was one I hadn't thought of: it is more accessible to physically-limited gardeners.
I found two other variations I might consider if I repeat my experiment. Some of the writers believe the straw bales should be oriented differently from the way my article writer and I did it. They say the bales should be placed with the strings on the side – rather than on the top and bottom – for better water penetration and to keep the string from touching the ground and decaying. Others say that if the string is plastic or other synthetic, it can be on the bottom and that water penetration isn't much of an issue.
Secondly, some recommend chemical fertilizers high in nitrogen – ammonium nitrate or ammonium sulfate, specifically – to condition the straw for 10 - 12 days prior to planting. Over the course of that period several writers recommend adding more than two cups of the nitrogen fertilizer per bale and conclude with another cup of balanced 10-10-10 chemical fertilizer. I feel sure this would have a significant effect on the composting process, even in our dry climate. Some gardeners, of course, would prefer to stick with organic materials.